The furore over the prophet Muhammad cartoons hit a new peak last night when at least nine people were reported dead in the Libyan city of Benghazi after a mob set fire to the Italian consulate.

More than 1,000 protesters set upon the mission, setting cars alight and breaking windows, apparently angered by a minister in Silvio Berlusconi's government who has said he intends to wear T-shirts bearing some of the cartoons.

An Italian consular official said nine protesters had been killed and several more had been wounded as armed police clashed with the crowd. State television showed part of the consulate on fire.

Italian state-owned RAI television said six members of the consular staff were trapped inside, but unhurt. RAI said anger mounted at the actions of Roberto Calderoli, the minister for constitutional reform, and a leading member of the xenophobic Northern League. Earlier this week, he announced that he planned to wear T-shirts featuring the cartoons that were published in European newspapers and have sparked violent protests around the world. Last night Mr Berlusconi asked for Mr Calderoli to resign.

The row also showed no signs abating in Pakistan where a cleric offered a £600,000 reward to anyone who killed the Danish cartoonists. Muhammad Yousef Qureshi, the leader of the hardline Jamia Ashrafia religious school in Peshawar, announced the bounty after Friday prayers. The reward also included a Toyota car, he said.

"This is a unanimous decision by all imams of Islam that whoever insults the prophet deserves to be killed and whoever will take this insulting man to his end, will get this prize," Mr Qureshi said. "This killing will enhance respect for Islam and for Muslims. Next time nobody will dare to commit blasphemy against our prophet," he told the Guardian.

The threat follows five days of violent protests in Pakistan, which have seen demonstrators ransack branches of Kentucky Fried Chicken. Several people have been shot dead. Thousands of police were deployed across the country yesterday to prevent further unrest. Pakistan announced it was withdrawing its ambassador to Denmark for consultations. Denmark said it was shutting its embassy in Pakistan and would be represented by Germany.

The Danish paper Jyllands-Posten, which first published the cartoons last September, said it was not concerned by the reward.

Jan Lund, its foreign editor, said the 12 cartoonists were used to threats by now. "This doesn't have anything to do with us any more," he said. "It's got everything to do with religious groups who are trying to get rid of [the Pakistani president, Pervez] Musharraf."